1. Field of the Invention
Apparatus and methods consistent with the present invention relate to a host controller, and more particularly, to an USB host controller including a descriptor tracing apparatus.
2. Description of the Related Art
Universal serial bus (USB) is a serial bus standard for personal computer (PC) peripheral devices. USB supports plug & play and hot-swap such that re-booting or setup is not required for USB devices. Thus, USB devices can be easily installed and used. Owing to these advantages, USB is widely used for embedded systems as well as PCs.
An USB system includes an USB host and an USB device. Generally, the USB host is installed in a computing module such as a PC and operated as a master controlling overall data communication. The USB device is installed in a unit, which is connected to a host, such as a printer and a mouse for providing a specific function.
Meanwhile, a system-on-chip (SOC) is a semiconductor integrated circuit (IC) chip providing a plurality of functions by one chip. System size and system test time can be reduced, and system reliability can be improved using an SOC.
Various USB devices are currently available on the market. Generally, an USB host controller is included in an SOC formed to connect an USB device to an USB host.
FIG. 1 is a block diagram illustrating a related art system on chip with an USB host controller.
Referring to FIG. 1, a central processing unit (CPU) 102 and a plurality of masters 104 share system memory 114 through a system bus 106 and a memory interface 108. An USB host controller 110 is necessary to access the system memory 114 while communicating with an USB device 116.
However, when the USB host controller 110 accesses the system memory 114, one of the masters 104 may be exclusively in use of the system bus 106. In addition, the possibility of a memory error is high due to another complex reason.
Particularly, if an error occurs during the transmission of important descriptor information including device type, manufacturer, supportable USB version, the USB host controller 110 malfunctions, and it is difficult to find the reason of the malfunctioning of the USB host controller 110.